JPH0861178A - Fuel injection device and its control method - Google Patents

Abstract

PURPOSE: To realize stable and reliable fuel cut control even in a high speed operation area of an engine without impairing responsiveness of a spill valve in a fuel injection device to regulate a fuel injection quantity by controlling the spill valve so as to be opened and closed. CONSTITUTION: A valve of a type which has a valve structure where the opening area at valve opening driving time temporarily becomes larger than the opening area at ordinary valve opening time and opens and closes spill passages 23a and 23b of a fuel injection pump 1, is used as a spill valve (a solenoid valve) 30. The fact that the engine is put in a fuel cut area or in the fuel cut area and a prescribed high speed operation area is detected on the basis of an engine operating condition, and when these operation areas are detected, the spill valve 30 is driven so as to be opened just before a fuel force feed stroke of the fuel injection pump 1. That is, in order to secure the spill area capable of temporarily releasing pressure of a high pressure chamber 14 about to be raised by the fuel force feed stroke, the spill valve 30 is run idle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for controlling the opening timing of a spill valve to adjust the injection amount when fuel is injected into a diesel engine by a fuel injection pump, and a control method thereof. In particular, the present invention relates to a device configuration and a spill valve control method which are useful for ensuring stability of fuel cut in a high speed range of an engine.

[0002]

2. Description of the Related Art As shown in, for example, Japanese Patent Laid-Open No. 58-187537, a fuel injection device such as the diesel engine has a spill passage between a high pressure chamber and a low pressure chamber of a fuel injection pump. By providing the spill passage and controlling the opening and closing of the spill passage by the spill valve, the amount of fuel pressure-fed from the high-pressure chamber to the nozzle, that is, the fuel injection amount is adjusted.

Further, in such a fuel injection device, the target injection amount of fuel is usually calculated based on the engine speed of the engine and various other operating conditions, and (A) the fuel injection range of the engine is normal. If in the control area,
The valve opening timing (OFF timing) of the spill valve is obtained based on the calculated target injection amount. Then, after the spill valve is closed every time the drive shaft rotation angle (cam angle) of the fuel injection pump reaches a predetermined angle, the rotation angle of the pump drive shaft corresponds to the obtained valve opening timing. The spill valve is opened at every angle. (B) If the engine operating range is in the low load fuel cut range, the driving of the spill valve is prohibited. That is, the spill passage of the fuel injection pump is maintained in the open state so that the fuel is neither pumped nor injected. (C) If the operating range of the engine is in the overrun range, the driving of the spill valve is prohibited in this case as well, so that the fuel is neither pumped nor injected. Such as,
It ensures the stable operation of the engine.

[0004]

By performing fuel injection and fuel cut control in this manner for each operating region of the engine, stable operation of the engine is certainly maintained.

By the way, according to such a fuel injection device, the fuel cut control is performed in a state where the spill valve is opened even when the engine is in a high speed and low load operation range. However, even in such a high-speed low-load operation range, even if the spill valve is opened to maintain the spill passage of the fuel injection pump in an open state, the pressure in the high pressure chamber is considerably high due to the lift of the cam. Becomes

Therefore, in order to surely cut off the fuel injection to the engine, in order to spill all the fuel delivered by the fuel injection pump into the low pressure chamber, it is necessary to naturally secure a large valve opening area of the spill valve. Occurs.

This is solved by increasing the valve stroke of the spill valve. However, in a spill valve that normally uses a solenoid valve, if the valve stroke is increased, this time, on the contrary, the responsiveness of the spill valve will decrease, and the metering accuracy will be impaired. I might have come to.

The present invention has been made in view of these circumstances, and it is possible to realize stable and reliable fuel cut control even in the high speed operation range of the engine without impairing the responsiveness of the spill valve. An object of the present invention is to provide a fuel injection device and a control method thereof.

[0009]

In order to achieve such an object, the invention according to claim 1 has a valve structure in which the opening area at the time of valve opening drive is temporarily larger than the opening area at the time of normal valve opening. Then, the spill valve that opens the spill passage of the fuel injection pump to stop fuel injection, the fuel cut area detection means that detects that the engine is in the fuel cut area, and the detection means When it is detected that the spill valve is open, the fuel injection device is configured with spill valve control means for driving the spill valve to open at a timing near the start of the fuel pressure pumping stroke of the fuel injection pump.

According to the second aspect of the invention, the spill passage of the fuel injection pump during valve opening has a valve structure in which the opening area when the valve is opened is temporarily larger than the opening area when the valve is normally opened. Spill valve for opening the fuel injection and stopping the fuel injection, high speed fuel cut area detection means for detecting that the engine is in the fuel cut area and at a predetermined speed or more, and the engine is in the high speed fuel cut area by this detection means. When the effect is detected, the fuel injection device is configured with spill valve control means for driving the spill valve to open at a timing near the start of the fuel pressure pumping stroke of the fuel injection pump.

According to a third aspect of the present invention, in the structure of the first or second aspect of the invention, the fuel injection pump is a fuel injection pump that pumps fuel by a cam, and the spill valve is an electromagnet. When the electromagnetic valve is driven to be closed by energizing the electromagnet, and is opened by deenergizing the electromagnet, the spill valve control means releases the energization to the electromagnet to open the spill valve. It is configured such that the timing of the bias is constant with respect to the cam rotation phase of the fuel injection pump.

Further, in the invention according to claim 4, in the constitution of each of these inventions, the spill valve has a movable stopper for positioning a normally open position of the valve in a state of being biased by the biasing means, When the valve is opened, the movable stopper displaces in the direction in which the movement of the valve in the valve opening direction is expanded against the biasing force of the biasing means. It is supposed to be done.

Further, according to the invention of claim 5, the spill passage of the fuel injection pump is opened / closed by having a valve structure in which the opening area when the valve is opened is temporarily larger than the opening area when the valve is normally opened. As a control method of a fuel injection device that includes a spill valve and opens the spill valve during a fuel pressure pumping stroke of a fuel injection pump to stop fuel injection to an engine, the fuel injection device is provided when the engine is in a fuel cut region. The spill valve is driven to open at a timing near the start of the fuel pressure feeding stroke of the pump.

According to the sixth aspect of the invention, similarly, the spill passage of the fuel injection pump is opened / closed by using a valve structure in which the opening area when the valve is opened is temporarily larger than the opening area when the valve is normally opened. As a control method of a fuel injection device that includes a spill valve that opens and opens the spill valve during the fuel pressure pumping stroke of the fuel injection pump to stop the fuel injection to the engine, In the above case, the spill valve is driven to open at a timing near the start of the fuel pressure pumping stroke of the fuel injection pump.

[0015]

According to the first aspect of the present invention, through the fuel cut area detection means and the spill valve control means: On condition that the engine is in the fuel cut area, near the start of the fuel pressure feed stroke of the fuel injection pump. This spill valve is driven to open at the timing. By performing such control, for example, in the high-speed operation range described above, even when the pressure of the high pressure chamber is normally increased with the fuel pressure pumping stroke of the fuel injection pump, at the start of the fuel pressure pumping stroke. The spill valve opening drive of the spill valve allows the spill area to be temporarily expanded when the pressure is about to be increased, as compared with the case where the spill valve is opened long before the same pressure feeding stroke. Become.

Therefore, even in the high speed operation range of the engine, the pressure increase of the pressure chamber in such a fuel cut range can be preferably avoided, and stable and reliable fuel cut control can be realized. Become.

Further, according to the above-mentioned valve structure of the spill valve, the valve stroke of the spill valve is enlarged only for a period of time required for the valve opening drive in order to secure a large spill area. Even if it is done, the responsiveness as the spill valve is not impaired.

Here, the "near the start of the fuel pressure pumping stroke of the fuel injection pump" in which the spill valve is driven to open does not refer to an absolute timing based on a specific point in the stroke, After that, the valve stroke of the spill valve is maximum, that is, fully opened to broadly indicate the time when the pressurization of the high pressure chamber can be efficiently suppressed.

On the other hand, in the invention described in claim 2, in place of the fuel cut region detecting means of the invention described in claim 1, it is detected that the engine is in the fuel cut region and at a predetermined rotational speed or more. And a spill valve control means, when the high speed fuel cut area detection means detects that the engine is in the high speed fuel cut area, the fuel injection stroke of the fuel injection pump is started. It is configured to drive the spill valve to open at a timing near it.

According to this structure of the second aspect of the invention, the valve opening drive of the spill valve in the fuel cut region is executed only in the high speed operation region in which the rotation speed is equal to or higher than the predetermined rotation speed. .

That is, the execution can be ensured only in the high-speed operation region where the operation such as the valve opening drive in the fuel cut region of the spill valve, which should not be necessary originally, works really effectively. When the spill valve is composed of a solenoid valve, the power consumption can be reduced.

According to the invention of claim 3,
When the fuel injection pump is a cam fuel injection pump and the spill valve is a solenoid valve which is closed by energizing the electromagnet and opened by deenergizing the electromagnet, the spill valve control means is provided. The timing of releasing the power supply to the electromagnet to drive the spill valve to open is set to a constant timing with respect to the cam rotation phase of the fuel injection pump. In other words, if the valve opening (OFF) timing of the driving operation in the fuel cut region of the spill valve or in the high speed operation region is set as a constant, the valve opening timing calculation is performed. The calculation time for will be automatically saved.

Normally, in such a fuel injection device, the arithmetic processing is executed in a cycle corresponding to the operating speed of the engine, so that if the valve opening timing for driving the spill valve is set to a constant value in this way. In particular, even in the high speed operation range, the process for calculating the valve opening timing does not become a bottleneck.

Further, according to the invention of claim 4,
The spill valve has a movable stopper that positions the normally opened position of the valve in a state of being biased by the biasing means, and the movable stopper resists the biasing force of the biasing means when the valve is driven. Then, the opening area at the time of driving the valve is enlarged based on the displacement in the direction in which the movement of the valve in the valve opening direction is enlarged. Can be configured as. With such a configuration, the above-mentioned valve structure "the opening area when the valve is opened temporarily becomes larger than the opening area when the valve is normally opened" as the spill valve can be easily realized.

On the other hand, a spill valve having a valve structure in which the opening area when the valve is opened is temporarily larger than the opening area when the valve is normally opened is provided for opening and closing the spill passage of the fuel injection pump.
As a control method of the fuel injection device for opening the spill valve during the fuel pressure stroke of the fuel injection pump to stop the fuel injection to the engine, as in the invention according to claim 5, In the above condition, the spill valve is driven to open at a timing near the start of the fuel pressure pumping stroke of the fuel injection pump. If such a method is adopted, even in this case, for example, even in the high-speed operation range, even when the pressure of the high pressure chamber is normally increased along with the fuel pressure pumping stroke of the fuel injection pump, the The spill valve opening drive causes the spill area to temporarily expand just when the pressure is about to be increased, compared with the case where the spill valve is opened long before the same pressure stroke. .

Therefore, even in the high speed operation range of the engine, the pressure increase of the pressure chamber in such a fuel cut range can be preferably avoided, and stable and reliable fuel cut control can be realized. become.

Here again, the phrase "near the start of the fuel pressure pumping stroke of the fuel injection pump" in which the spill valve is driven to open does not refer to an absolute timing based on a specific point in the stroke, but after that. The spill valve has a maximum valve stroke, that is, the valve stroke is fully opened, so that the pressurization of the high-pressure chamber can be efficiently suppressed.

As a control method of the fuel injection device,
According to the invention described in claim 6, when the engine is in the fuel cut region and at a predetermined speed or more, the spill valve is driven to open at a timing near the start of the fuel pressure pumping stroke of the fuel injection pump. If such a method is adopted, the opening drive of the spill valve in the fuel cut region will be executed only in the high speed operation region in which the above-mentioned predetermined number of revolutions or more is achieved. In that case, the power consumption can also be reduced.

[0029]

1 shows an embodiment of a fuel injection device according to the present invention. The fuel injection device of this embodiment, when injecting fuel into a diesel engine or the like by a fuel injection pump,
This device is configured as a device that can control the valve opening timing of the spill valve to adjust the injection amount thereof, and can also sufficiently secure the stability when fuel is cut in the high speed operation range of the engine.

The device of this embodiment shown in FIG. 1 is an injection device using a face cam type fuel injection pump, but in FIG. 1, for the sake of convenience, only the main parts of this fuel injection pump are shown. Illustration of the vane feed pump and the like arranged on the left side is omitted.

First, the structure of this fuel injection pump and the structure of a spill valve (electromagnetic valve) used as a metering valve of the pump will be described. In the face-cam type fuel injection pump 1 shown in FIG. 1, a drive shaft 3 that rotates in synchronization with a crankshaft (not shown) of a diesel engine is arranged in the pump housing 2.

In the fuel injection pump 1, a feed pump (not shown) rotates in response to the rotation of the drive shaft 3 so that fuel is supplied to the fuel chamber (low pressure chamber) 5.

On the other hand, a pulsar 4 having a large number of teeth on its outer peripheral surface is attached to the drive shaft 3, and a cam is formed at the right end portion of the drive shaft 3 in the figure through a coupling (not shown). The plates 6 are connected. In addition, one side surface (left side in the drawing) of the cam plate 6 is provided with the same number of face cams 6a as the number of cylinders of the diesel engine to which fuel is supplied.

A roller ring 7 is arranged between the pulsar 4 and the cam plate 6. The face ring 6 of the cam plate 6 is also attached to the roller ring 7.
A plurality of cam rollers 8 facing a are attached.

In the fuel injection pump 1, a head portion 2a is provided on the right side of the pump housing 2 in the figure. The head 2a has a plunger hole 11
A cylinder 10 having a
Further, a plunger 12 integrally supported by the cam plate 6 is slidably and rotatably disposed in the plunger hole 11 of No. 0.

The cam plate 6 is engaged with the cam roller 8 in such a manner that the face cam 6a thereof is constantly pressed by the cam roller 8 by being urged by the plunger spring 13. Therefore, the cam plate 6 and the plunger 12 integrally supported by the cam plate 6 rotate due to the rotation of the drive shaft 3, and the face cam 6a and the cam roller 8 are engaged with each other. It will reciprocate in the middle and left and right directions.

In the head portion 2a, the cylinder 10 and the end surface of the plunger 12 are provided with a pressurizing chamber (high pressure chamber).
14 is formed. Intake groups 15 for the number of cylinders of the diesel engine are formed on the peripheral surface near the end of the plunger 12, and one of the intake groups 15 communicates with the intake passage 16 as the plunger 12 rotates. As a result, fuel is sucked from the fuel chamber 5 into the pressurizing chamber 14.

Further, the fuel sucked into the pressurizing chamber 14 is pressurized as the plunger 12 moves to the right in the figure due to the above-mentioned reciprocating motion, and the pressurized fuel is further It is pressure-fed to the injection passage 19 through the communication passage 17 and the distribution port 18. Then, the fuel pressure-fed to the injection passage 19 is fed to the fuel injection nozzle 21 via the delivery valve 20, and is injected and fed from the nozzle 21 into the combustion chamber of the diesel engine.

On the other hand, the head portion 2a is provided with fuel passages (spill passages) 23a and 23b for connecting the pressurizing chamber (high pressure chamber) 14 and the preceding fuel chamber (low pressure chamber) 5 to each other. Of the passages, the passage 23a is a high-pressure side passage and the passage 23b is a low-pressure side passage.
The solenoid valve 30 that functions as a spill valve of the fuel injection pump 1 controls the opening and closing, that is, the presence or absence of communication.

Incidentally, in the fuel injection pump 1, when the spill passages 23a and 23b are opened (communication) by the solenoid valve 30, the fuel pressurized through the pressurizing chamber 14 is supplied to the fuel chamber (low pressure chamber) 5 The fuel injection through the nozzle 21 is stopped (cut).

On the other hand, in the fuel injection pump 1, the fuel chamber 5 in the pump housing 2 is provided with a rotation speed sensor 22 integrally attached to the roller ring 7. The rotation speed sensor 22 including an electromagnetic pickup coil detects a passage of a tooth provided on the outer peripheral surface of the pulsar 4 and also serves as a reference timing signal Ne at a constant timing corresponding to the plunger lift described above.
Is output to the electronic control unit 50.

The electronic control unit 50 inputs the accelerator opening signal of the vehicle and the cooling water temperature information of the diesel engine together with the timing signal Ne so as to inject fuel according to the operating state of the engine. A device for controlling the valve opening / closing timing of the solenoid valve 30.

The control command from the electronic control unit 50 is
It is input to the drive circuit 60, and through this drive circuit 60,
The electromagnetic valve 30 (more precisely, the electromagnet 40 thereof) is turned on / off, that is, converted into a signal for energizing / de-energizing.

Next, the internal structure of the solenoid valve 30 will be described. In the solenoid valve 30, a valve body 31 is provided in a valve housing 32 mounted on the head portion 2a of the fuel injection pump 1.

The valve body 31 is provided with spill passages 23a and 23b corresponding to the high pressure chamber (pressurization chamber) 14 and the low pressure chamber (fuel chamber) 5, respectively, and these passages are extended by a valve spring 33. Normally, the valve element 34 is urged toward the valve opening side to open and close.

The valve body 34 is formed with a tapered abutment portion 34a at its lower end, and the valve body 31 is provided with a valve seat 31a at a portion facing the corresponding abutment portion 34a of the valve body 34. Are formed. Then, when the valve body 34 is closed, the contact portions 34a and the valve seat 31a are closely contacted to close the passages 23a and 23b.

On the other hand, the back surface 34b of the valve element 34 is in contact with an armature shaft 36 which is integrally formed with and supports the armature 35. That is, the electromagnet 40
When current is applied from the drive circuit 60 to the coil constituting the armature through the lead wire 41, the armature 3
5 is attracted to this electromagnet 40. With the suction of the armature 35, the armature shaft 36 pushes down the valve body 34 against the urging force of the valve spring 33, and thus the contact portion 34a and the valve seat 31a are in contact with each other in a closed state. Lead to.

In the solenoid valve 30, a movable stopper 38 is provided inside the valve housing 32, and is supported by a stopper spring 37 so as to be urged downward in the figure.

The movable stopper 38 is provided on the rear surface 34 of the valve body 34 in a state where the solenoid valve 30 is normally supported and biased as described above.
The valve position of the valve element 34 at the time of the normal valve opening is positioned in the state of being in contact with b and being in contact with it. Then, when the electromagnet 40 is not energized, the urging force of the valve spring 33 and the stopper spring 3 are kept in this state.
It is designed to maintain a balance with the bias of 7. However, when the valve body 34 is closed by the energization of the electromagnet 40 and then the energization is released and the valve body 34 is driven to open the valve, the energizing force of those energizing forces is temporarily increased in the mode shown in FIG. The balance is broken, and the movable stopper 38 and the movable stopper 38 are both displaced in the valve opening direction beyond the above-mentioned positioned valve position.

That is, in FIG. 2A, when the solenoid valve 30 is normally opened (non-energized), the urging forces of the springs 33 and 37 are balanced and the valve position of the valve element 34 is shown in FIG. 2B shows a state in which the solenoid valve 30 is positioned, and FIG. 2B shows a closed state of the solenoid valve 30 based on energization of the electromagnet 40. As shown in these figures, the solenoid valve 30
When the valve is normally opened, an opening area corresponding to the distance L1 is secured, and even when the valve is closed, the valve stroke corresponding to the distance L1 is provided and the valve is closed with good responsiveness. In each of these figures, the distance L2 indicates the movable distance (movable stroke) of the movable stopper 38.

On the other hand, in FIG. 2, FIG. 2 (c) shows a state immediately after the solenoid valve 30 is driven to open based on the de-energization of the electromagnet 40. As shown in FIG. 2 (c), the solenoid valve 30 has a valve body 34 immediately after its opening (1) due to the urging force of the valve spring 33.
Moves in the valve opening direction (upward in the figure). (2) The back surface 34b of the valve body 34 is brought into contact with the movable stopper 38. (3) The movable stopper 38 brought into contact with the stopper spring 37 due to the urging force of the valve spring 33 and the pressure of the fuel rapidly flowing from the high pressure chamber 14 (spill passage 23a) to the low pressure chamber 5 (spill passage 23b). The valve element 34 and the like are displaced in the valve opening direction against the biasing force of the valve. In addition, the displacement of each of these parts depends on the valve housing 3.
2 to the fixed stopper 39 provided on the armature 3
It is regulated by abutting the upper end of 5. It will be driven in such a mode. And at this time, the valve body 3
4 is opened with a valve stroke corresponding to the sum (L1 + L2) of the valve stroke L1 when the valve is closed and the movable stroke L2 of the movable stopper 38, and the valve stroke (L1 + L2) is also used as the spill passage. A large opening area corresponding to is secured. However, this state is temporary immediately after the solenoid valve 30 is opened, and is eventually returned to the normally opened state shown in FIG. 2A by the urging force of the stopper spring 37. .

In this way, the solenoid valve 30 realizes a two-stage valve stroke having different opening areas at the time of normal valve opening and one timing when it is driven to open. The relationship between these opening areas is: temporary opening area during valve opening drive> opening area during normal valve opening.

Next, the fuel injection control processing as the apparatus of the embodiment executed by the electronic control unit 50 will be described on the premise of the valve structure of the solenoid valve 30. In the electronic control unit 50, the control information of the solenoid valve 30 is set and the setting is performed in the procedure shown in FIGS. 4 to 6, for example, corresponding to various operating ranges of the diesel engine shown in FIG. Drive control based on information is executed.

First, the control information setting procedure of the solenoid valve 30, which is the main routine of the control device 50, will be described with reference to FIG. This main routine is
Rotational speed NE calculated based on the timing signal Ne
Is in the range of 300 to 2000 rpm, the process is executed, for example, every half rotation of the drive shaft 3 in synchronization with the same timing signal Ne, and when the number of revolutions is higher than that, for example, a cycle of every 8 ms (millisecond). Shall be executed in.

Now, in such a main routine,
First, in step 101, the electronic control unit 50 calculates the target injection amount Qfin by the fuel injection pump 1.
To calculate the target injection amount Qfin, for example, (1) the basic injection amount (Qbase) is calculated based on the rotational speed NE and the accelerator opening of the vehicle. (2) The calculated basic injection amount (Qbase) is corrected based on the cooling water temperature information of the engine. Such a method is used. Incidentally, the basic injection amount, the compatible value of the basic injection amount corresponding to each value of the possible rotation speed and accelerator opening is registered in advance in the memory as a map,
The value of the basic injection amount corresponding to the values of the rotational speed and the accelerator opening can be obtained by reading each time.

The control device 50, which has calculated the target injection amount Qfin in this way, then determines the operating range of the engine through the following determination processes. For example, in steps 102 and 103 of the main routine, the rotational speed NE is 50
When it is determined that the speed is less than 00 rpm and less than 2500 rpm, or in step 103, the rotation speed N
Even if E is determined to be 2500 rpm or more, if it is determined in step 110 that the calculated injection amount Qfin exceeds 15 cubic / stroke, the control device 50 determines that the engine is It is determined that it is in the normal control area shown as the area (A).

Then, the control device 50, which has thus determined that it is in the normal control range, calculates the OFF timing of the solenoid valve 30, that is, the valve opening timing in step 104. Here, for example, the value of the target injection amount Qfin thus obtained is converted into time and angle based on the number of teeth of the pulsar 4 and the like.

The control device 50 which has calculated the solenoid valve OFF timing (valve opening timing) further registers the calculated value of the obtained valve opening timing in an appropriate data memory in step 105, and then proceeds to step 106. Then, if the solenoid valve ON prohibition flag, which will be described later, is set, it is released.

On the other hand, in step 102, the rotational speed NE
Is less than 5000 rpm, the same rotational speed NE is determined to be 2500 rpm or more in step 103, and the calculated injection amount Qfin is 15 cubic / stroke or less in step 110. If so, the control device 50 determines that the engine is in the low load fuel cut region shown as the region (B) in FIG. 3.

In step 111, the controller 50, which has determined that the fuel cut range is in effect, sets a predetermined flag to a solenoid valve ON prohibition flag for prohibiting energization of the solenoid valve 30, that is, closing of the solenoid valve 30. Set in memory.

On the other hand, although it is determined in step 102 that the rotational speed NE is 5000 rpm or more,
When it is determined in step 120 that the rotational speed NE is less than 6000 rpm, the control device 50 determines that the engine is in the overrun region shown as the region (C) in FIG. 3.

In this case, the control device 50, which has determined that it is in the overrun region, also sets the solenoid valve on-prohibition flag for prohibiting the energization of the solenoid valve 30 in step 121 so as to cut off the fuel injection. Set in flag memory.

In step 102, the rotational speed NE
Is determined to be 5,000 rpm or more, and when it is determined in step 120 that the rotational speed NE is 6000 rpm or more, the control device 50 indicates that the engine is the area (D) in FIG. It is determined that the solenoid valve is in the blank area.

The solenoid valve blank region is a region newly set as a control region for the high-speed operating region in the apparatus of the embodiment, and the control device determines that the engine is in the solenoid valve blank region. In step 131, the 50 registers the solenoid valve OFF timing constant prepared in advance in the data memory. This solenoid valve off-timing constant is, for example, a value corresponding to the off-timing (valve-opening timing) of the solenoid valve 30 calculated at step 104, provided that the timing is just before the fuel pressure delivery stroke of the fuel injection pump 1. The corresponding value is a constant value prepared in advance.

In this way, the control device 50, in which the solenoid valve OFF timing constant is registered in the memory, further confirms in step 132 whether or not the solenoid valve ON prohibition flag is set, and if the flag is set, this is checked. Is canceled and this routine ends.

Next, with reference to FIG. 5 and FIG. 6, the procedure for calculating the rotational speed NE of the electronic control unit 50 and the procedure for driving the solenoid valve 30 which are executed as an interrupt process by the timing signal Ne will be described.

First, the Ne interrupt routine 1 shown in FIG. 5 is a routine that is activated and executed every 4 pulses of the timing signal Ne, for example. That is, the control device 5
0 reads the pulse interval time at each time (step 202) through the routine that is started each time the timing signal Ne reaches the fourth pulse (step 201),
The rotation speed NE is calculated based on the read pulse interval time (203). The rotational speed NE thus calculated is
It will be used for determining the engine operating range in the main routine (FIG. 4) described above.

Further, the Ne interrupt routine 2 shown in FIG. 6 is a routine which is started and executed at every rise (or fall) of the timing signal Ne. In FIG. 6, for convenience, the on-time monitoring and the off-time monitoring of the solenoid valve 30 are shown together in one flowchart, but in reality, these on-time monitoring and off monitoring are performed. It is executed as a routine independent of time-consuming monitoring.

That is, in the interrupt routine, the controller 50 turns on the solenoid valve 30 which is automatically determined based on the rotation phase of the face cam 6a every time the timing signal Ne rises (or falls) (step 301). First, it is determined whether or not the time (valve closing timing) has been reached (step 302). If the solenoid valve on-time has been reached, the condition that the solenoid valve on-prohibition flag described above is not set in the flag memory (step 30
3), the solenoid valve 30 is turned on. That is, the solenoid valve 30 is driven to close (step 304).

On the other hand, the control device 50 causes the timing signal Ne to rise (or fall) (step 3).
01), referring to the OFF time of the solenoid valve 30 registered in the above-mentioned data memory, the OFF time of the solenoid valve 30,
That is, it is determined whether the valve opening time has been reached (step 305). When the solenoid valve off time is reached, the solenoid valve 30 is turned off. That is, the solenoid valve 3
0 is driven to open the valve (step 306).

If none of these conditions is satisfied, the system waits until the next interrupt by the same timing signal Ne. Thus, the electronic control unit 50 shown in FIG.
~ By repeating the process of FIG. 6, in the fuel injection pump 1 including the electromagnetic valve 30 as the spill valve, in the mode shown in FIG. 7 or FIG. The fuel injection operation and fuel cut operation are controlled.

The operation of the apparatus of this embodiment will be described in further detail below with reference to FIGS. 7 and 8. First, when the engine is in the normal control range (region (A) in FIG. 3), the fuel injection pump 1 including the solenoid valve 30 is operated as shown in FIG.
The fuel injection operation is controlled in the manner indicated by the solid line.

That is, now, with respect to the lift operation of the face cam 6a shown in FIG. 7A, the time t is shown in FIG. 7B.
The solenoid valve 3 corresponding to the timing indicated by 11
It is assumed that an ON time of 0 (valve closing timing) is set.

Further, in the same operating range, the above-mentioned calculation of the electromagnetic valve OFF timing is executed through the electronic control unit 50 (step 104 in FIG. 4), and the timing is shown as time t13 in FIG. 7 (b). It is set according to the timing and registered in the memory.

In such a situation, when the Ne interrupt routine 2 (FIG. 6) described above is executed by the control device 50, the solenoid valve 30 first operates at the time t1.
Corresponding to 1, the energization of the electromagnet 40 is started. Then, the valve closing operation described above is started with this energization,
As shown in FIG. 7C, the valve body 34 closes the spill passages 23a and 23b while being lifted by the distance L1.

On the other hand, in the high pressure chamber 14, due to the closing of the solenoid valve 30, the fuel pressure feeding process of the pump 1 started at time t12, that is, with the lift operation of the face cam 6a, as shown in FIG. The pressure is increased in the mode shown in e), and the fuel injection by the pump 1 is started in the mode shown in FIG. 7 (f). In addition, here, the pressure level OP shown by the one-dot chain line in FIG.
Indicates a threshold pressure at which the fuel injection valve (fuel injection nozzle 21) opens.

After that, when the solenoid valve off time is determined corresponding to the time t13 and the energization of the electromagnet 40 is released, the solenoid valve 30 is operated in the mode shown in FIG. 2 (c). With the valve opening drive, as shown in FIG. 7C, the valve element 34 is lifted greatly in the valve opening direction over the distance L1 + L2 for a period of time. FIG. 7D shows a lift mode of the movable stopper 38 at this time.

By thus opening the valve element 34 with a large opening area, the fuel pressure in the high pressure chamber 14 is quickly reduced at the time t13, and the fuel being injected is also the same. It will be cut promptly at time t13. That is, in this normal control area,
The aforementioned valve structure of the solenoid valve 30 realizes so-called sharp cut of injected fuel.

On the other hand, when the engine is in the low load fuel cut region (region (B) of FIG. 3) or the overrun region (region (C) of FIG. 3), the solenoid valve 30 is also used.
Including the above, the fuel injection operation of the fuel injection pump 1 is controlled in the manner shown by the broken line in FIG. 7.

That is, in these operating ranges, the solenoid valve ON prohibition flag described above is set in the main routine shown in FIG. 4 (step 111 or 12 in FIG. 4).
1) Regardless of whether or not the times t11 and t13 are set, the solenoid valve 30 is maintained in the non-energized state, that is, the normally open state shown in FIG.

Therefore, even if the face cam 6a is lifted as shown in FIG. 7 (a), the pressure in the high pressure chamber 14 is not increased, and therefore the fuel is not injected. That is, the engine is maintained in the fuel cut state.

When the engine is in the solenoid valve blank area (area (D) in FIG. 3) which is located in a higher speed area than the overrun area, the solenoid valve 30 is included in the above area. In the fuel injection pump 1, the fuel cut operation is controlled in the mode shown by the solid line in FIG.

In this operating range, as compared with the lift operation of the face cam 6a shown in FIG. 8A, FIG.
It is assumed that the ON time (valve closing timing) of the solenoid valve 30 is set in correspondence with the timing shown as time t21.

For the same operating range, the above-mentioned solenoid valve OFF timing constant is prepared in advance corresponding to the timing shown as time t22 in FIG. 8B, and this is registered in the memory through the electronic control unit 50 ( Figure 13 Step 13
1). In this example, the time t22 is
It is assumed that the timing is set immediately before the lift operation of the face cam 6a shown in FIG. 8A, that is, the timing CL immediately before the fuel pressure pumping stroke of the fuel injection pump 1.

In the same operating range, the solenoid valve ON prohibition flag is not set, though it is in the fuel cut range (step 132 in FIG. 4). In such a situation, when the Ne interrupt routine 2 (FIG. 6) described above is executed by the control device 50, the solenoid valve 30 first starts to energize the electromagnet 40 corresponding to the time t21. To be done. Then, with the energization, the above-described valve closing operation is started, and the valve body 34 closes the spill passages 23a and 23b in a state of being lifted by the distance L1 as shown in FIG. 8C.

After that, when the solenoid valve off time is determined corresponding to the time t22 and the energization of the electromagnet 40 is released, the solenoid valve 30 is operated in the manner shown in FIG. 2 (c). With the valve opening drive of FIG.
As shown in (c), the distance L1 + L2
The valve lifts greatly in the valve opening direction. FIG.8 (d) is
The lift mode of the movable stopper 38 at this time is shown.

Since the valve element 34 is opened with a large opening area in this way, in the high pressure chamber 14,
When the fuel pressure is about to be increased along with the lift operation of the face cam 6a, the spill area is enlarged, and the boosting is suitably avoided as shown by the solid line in FIG. 8 (e). Like And for this reason, FIG.
As indicated by the solid line in (f), unnecessary fuel injection is not performed.

In such a high speed operation range, even when the solenoid valve 30 is maintained in the normally open state,
With the lift operation of the face cam 6a, for example, FIG.
As described above, the fuel in the high pressure chamber 14 is pressurized in the manner indicated by the broken line in (e), and unnecessary fuel injection is performed in the manner indicated by the broken line in FIG. 8 (f). Is. Also in FIG. 8 (e), the pressure level OP indicated by the one-dot chain line indicates that the fuel injection valve (fuel injection nozzle 2
1) shows the threshold pressure at which the valve opens.

As described above, according to the apparatus of this embodiment, even in the high speed operation range of the engine, the so-called idling of the solenoid valve 30 suitably avoids the boosting of the pressure chamber in the fuel cut range. Become so. As a result, stable and reliable fuel cut can be realized.

Further, according to the above valve structure of the solenoid valve 30,
In order to secure the large opening area described above, the valve stroke of the valve is expanded to the distance L1 + L2 only at one time when it is driven to open, and in the normal valve opening state, the distance L1 The valve stroke corresponding to is maintained.
Therefore, the responsiveness of the solenoid valve 30 used as the spill valve is not impaired.

In the apparatus of the present embodiment, the above-mentioned idle driving control of the solenoid valve 30 is executed only in the high speed operation range where the rotational speed NE is 6000 rpm or more.
Alternatively, for example, it is also possible to adopt a configuration in which this idle driving control is executed in all the operating regions that are the fuel cut region.
However, in this case, the solenoid valve is driven in all operating regions of the engine, which is somewhat disadvantageous in terms of power consumption. In this sense, the device of the embodiment, which executes the idle shot control of the solenoid valve 30 only in the high speed operation range, has a stable fuel injection with the minimum power consumption over the entire operation range of the engine. In addition, it can be said that the device realizes fuel cut control.

Further, in the apparatus of the embodiment, this solenoid valve 30
In the idle driving control, the valve opening driving timing is set to the timing immediately before the lift operation of the face cam 6a, but the valve opening driving timing setting in such a mode is not always correct.

That is, even if it is called a cam lift operation for a single port, there are various modes of starting the fuel pressure feeding, and the mode of boosting the fuel pressure in the high pressure chamber 14 also differs depending on the mode of starting the fuel pressure feeding. Become.

Strictly speaking, the valve opening drive timing of the solenoid valve 30 may be, for example, a pressure increasing mode of the high pressure chamber 14 or
By considering the factors such as the valve opening response speed of the solenoid valve 30 and the time for which a wide opening area is secured by this valve opening drive, the valve stroke of the solenoid valve 30 is maximized, that is, fully opened. The timing at which the pressurization of the high-pressure chamber 14 can be efficiently suppressed will be selected.

Further, in the apparatus of the embodiment, this solenoid valve 30
The valve opening timing (solenoid valve OFF timing) required for the idle driving is not calculated each time, but a constant timing is set for the rotation phase of the face cam 6a, so that high speed operation can be performed. The processing load on the electronic control unit 50 is reduced.

However, depending on the capability of the electronic control unit 50, it is of course possible to calculate and set a preferable time as the electromagnetic valve OFF time each time, for example, through map calculation or the like.

Further, in the apparatus of the embodiment, the solenoid valve 30 having the above valve structure is used as the spill valve, but the selection is also arbitrary. That is, as long as the spill valve used in the fuel injection device and the control method thereof of the present invention has a valve structure in which the opening area at the time of valve opening drive is temporarily larger than the opening area at the time of normal valve opening. Well, Figure 1 or Figure 2
It is not limited to the valve structure of the solenoid valve 30 illustrated in FIG.

[0098]

As described above, according to the present invention, pressure increase in the pressure chamber in the fuel cut region can be preferably avoided, and stable and reliable fuel cut control can be realized. become.

Further, according to the present invention, the valve stroke of the spill valve is enlarged only in the temporary period of the valve opening drive in order to secure a large spill area when avoiding the pressure increase of the pressure chamber in the fuel cut region. The responsiveness of the spill valve is not impaired.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of an embodiment of a fuel injection device according to the present invention.

FIG. 2 is a sectional view showing a mode in which the opening area of the solenoid valve (spill valve) shown in FIG. 1 is variable.

FIG. 3 is a graph showing an example of an engine operating range as a guide for spill valve control in the apparatus of the embodiment.

FIG. 4 is a flowchart showing a procedure for setting solenoid valve control information of the apparatus of the embodiment, which is executed corresponding to each operation range shown in FIG.

5 is a flow chart showing a rotation speed calculation procedure of the apparatus of the embodiment, which is interrupted based on the rotation speed sensor output shown in FIG.

6 is a flowchart showing a solenoid valve control procedure of the apparatus of the embodiment, which is interrupted based on the rotation speed sensor output shown in FIG.

FIG. 7 is a timing chart showing a solenoid valve control mode of the apparatus of the embodiment, which is executed corresponding to each of the normal control range, fuel cut range, and overrun range shown in FIG.

FIG. 8 is a timing chart showing a solenoid valve control mode of the apparatus of the embodiment, which is executed corresponding to the solenoid valve blank hit area shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 2 ... Pump housing, 2a ... Head part, 3 ... Drive shaft, 4 ... Pulser, 5 ... Fuel chamber (low pressure chamber), 6 ... Cam plate, 6a ... Face cam, 7 ... Roller ring, 8 ... cam roller, 10 ... cylinder, 11 ... plunger hole, 12 ... plunger, 13 ... plunger spring, 14 ... pressurizing chamber (high pressure chamber), 15 ...
Inhalation group, 16 ... Inhalation passage, 17 ... Communication passage, 18 ...
Distribution port, 19 ... Injection passage, 20 ... Delivery valve,
21 ... Fuel injection nozzle, 22 ... Rotation speed sensor, 23 (2
3a, 23b) ... Fuel passage (spill passage), 30 ... Solenoid valve (spill valve), 31 ... Valve body, 31a ... Valve seat, 32 ... Valve housing, 33 ... Valve spring, 34 ... Valve body, 34a ... Contact Part, 34b ... Back of valve body,
35 ... Armature, 36 ... Armature shaft, 37 ... Stopper spring, 38 ... Movable stopper, 39 ... Fixed stopper, 40 ... Electromagnet, 41 ... Lead wire, 50 ... Electronic control unit, 60 ... Driving circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Enomoto 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Prefecture Japan Auto Parts Research Institute, Inc.

Claims (6)

[Claims] 1. A valve structure having an opening area temporarily larger than that at the time of normal valve opening when the valve is opened, and a spill passage of a fuel injection pump is opened during valve opening to stop fuel injection. A spill valve, fuel cut area detection means for detecting that the engine is in the fuel cut area, and when this detection means detects that the engine is in the fuel cut area, the And a spill valve control means for driving the spill valve to open at a timing. 2. A valve structure in which an opening area when the valve is opened is temporarily larger than an opening area when the valve is normally opened, and a spill passage of a fuel injection pump is opened during valve opening to stop fuel injection. A spill valve, a high-speed fuel cut area detection means for detecting that the engine is in the fuel cut area and at a predetermined speed or more, and when the detection means detects that the engine is in the high speed fuel cut area, A fuel injection device, comprising: spill valve control means for driving the spill valve to open at a timing near the start of the fuel pressure feeding stroke of the injection pump. 3. The fuel injection pump is a fuel injection pump that pumps fuel by a cam, and the spill valve is a solenoid valve that is driven to close by energizing an electromagnet and opened to open when deenergizing the electromagnet. The spill valve control means sets a timing at which the electromagnet is de-energized to open and drive the spill valve at a constant timing with respect to a cam rotation phase of the fuel injection pump. 1. The fuel injection device according to 1 or 2. 4. The spill valve has a movable stopper for positioning a normally opened position of the valve in a state of being biased by the biasing means, and when the valve is driven, the movable stopper acts as the biasing means. 4. The fuel according to claim 1, 2 or 3, wherein the opening area when the valve is opened is expanded based on the displacement in a direction that expands the movement of the valve in the opening direction against the biasing force. Injection device. 5. A spill valve comprising a spill valve for opening and closing a spill passage of a fuel injection pump having a valve structure in which an opening area when driving to open a valve is temporarily larger than an opening area when normally opening. Is a method of controlling a fuel injection device that opens the fuel injection pump during the fuel pressure stroke of the fuel injection pump to stop fuel injection into the engine, and when the engine is in the fuel cut region, starts the fuel pressure stroke of the fuel injection pump. A method of controlling a fuel injection device, characterized in that the spill valve is driven to open at a timing near the same. 6. A spill valve having a spill valve for opening and closing a spill passage of a fuel injection pump having a valve structure in which an opening area when a valve is opened is temporarily larger than an opening area when a valve is normally opened. Is a method of controlling a fuel injection device that opens the fuel injection pump during the fuel pressure stroke of the fuel injection pump to stop fuel injection to the engine, wherein the fuel is A method of controlling a fuel injection device, characterized in that the spill valve is driven to open at a timing near the start of the fuel pressure stroke of the injection pump.